EXTENSIBLE ORGANIZATION OF PROPERTY DESCRIPTIONS IN OBJECT MODELING FOR ENGINEERING DESIGN

Object-oriented information systems capturing engineering-design prope rty information run into a problem of extensibility. While class hiera rchies defining generic engineering information may be developed accor ding to a classification based on science and general-purpose engineer ing, this leaves aside special-purpose properties such as those inspir ed by a particular type of artefact. These properties may be the decid ing factor in a particular design application of the data system; thus the ability to 'add in' property descriptions specified for a special ist view of a design function within an enterprise often determines th e practical usefulness of the object model adopted. Partitioned classe s are proposed as a modelling mechanism which addresses the need for ' upward customization' of generic knowledge. The solution allows the ex tension of any class to be partitioned between general- and special-pu rpose members. Advantages of this scheme over multiple inheritance are demonstrated using relational analysis, and they are illustrated by i ts implementation within an information retrieval system for the visua l display of property data.